BGP is a core routing protocol which maps options for the best available routes for traffic to flow across the net. Several routing options are normally included. The China BGP incident is the internet routing equivalent of TomTom publishing routes via Shanghai for motorists looking for alternative routes between London and Paris.

IDC China Telecommunication published ill-conceived routes for between 32,000 and 37,000 networks - about 10 per cent of the net - instead of the normal 40 or so routes, and this information was taken as viable routing options by many service providers for about 20 minutes early on Thursday morning (US time) after China Telecommunications republished it and before the mix-up was resolved. Routers in Asia would have been more likely to adopt the false routes as potentially viable, but effects of the incident were recorded all over the world.

BGPmon.net, a BGP monitoring service, has a detailed technical write-up of the snafu, which it described as a prefix hijack, here.

Although it seems they [IDC China Telecommunication] have leaked a whole table, only about 10 per cent of these prefixes propagated outside of the Chinese network. These include prefixes for popular websites such as dell.com, cnn.com, www.amazon.de, www.rapidshare.com and www.geocities.jp.

A large number of networks impacted this morning were actually Chinese networks. These include some popular Chinese website such as www.joy.cn , www.pconline.com.cn , www.huanqiu.com, www.tianya.cn and www.chinaz.com

A cock-up is suspected, rather than a conspiracy, at least by BGPmon.net.

Given the large number of prefixes and short interval I don’t believe this is an intentional hijack. Most likely it’s because of configuration issue, i.e. fat fingers. But again, this is just speculation.

The practical consequences of the screw-up are still being assessed but it could have resulted in dropped connections or, worse, traffic routed through unknown systems in China. The mess provides one of the clearest illustrations of the security shortcomings of BGP, a somewhat obscure but nonetheless important network protocol.

The China BGP global routing represents a rare but not unprecedented mix-up in global internet traffic management. For example, just two weeks ago bad routing data resulted in the redirection of Chilean internet traffic through a DNS (Domain Name System) server in China, as explained in a detailed post-mortem by internet monitoring firm Renesys here. Bad BGP routing information from Pakistan caused YouTube to briefly drop off the net back in 2008. ®